The quake was the strongest aftershock of more than 200 which have shaken the South American nation since the massive 8.8-quake of February 27 which sparked a killer tsunami and left almost 500 confirmed dead.
The latest aftershock was centred 114km south of Valparaiso, where it caused some to flee in panic from the Chilean parliament as right-wing tycoon Pinera prepared to take over power.
“I swear,” Pinera said as he took the oath of office, inheriting the presidential reins from popular left-wing leader Michelle Bachelet and now facing the huge challenge of rebuilding the nation.
But parliament was evacuated shortly afterwards as Chile still reels from one of the largest earthquakes ever recorded.
The National Emergency Office, sharply criticised for its slow reaction to February’s deadly quake, swiftly issued a tsunami alert for central areas of Chile, including Valparaiso.
But the Haiwaii-based Pacific Tsunami Warning Center said there was no threat of a “destructive widespread tsunami”.
Pinera’s first task as president was set to be a visit to the ravaged coastal town of Constitucion, one of the worst hit by last month’s quake and the giant waves that followed, that left some two million homeless.
It was not immediately clear whether the latest strong aftershock would alter his plans.
Pinera’s January victory spelled an end to the ruling left-wing coalition that has governed Chile since the end of General Augusto Pinochet’s dictatorship 20 years ago.
But his presidency will be marked by the aftermath of the quakes.
“We won't be the government of the earthquake, we’ll be the government of reconstruction,” Pinera said recently, naming five new governors in each of the worst-hit central regions.
The 60-year-old not only faces the challenge of reconstruction — which analysts estimate could cost up to $15 billion (€11bn) — but also takes over from a highly popular outgoing leader.
Bachelet scored an 84 % popularity rating in a post-quake survey, even amid criticism of a slow government reaction to the disaster.
Bachelet yesterday issued a farewell statement boasting that her left-wing Concertacion coalition had in the past 20 years turned Chile into “a country of high credibility”.
Pinera, a self-proclaimed centrist, has promised he will build on the policies practised by his predecessor, rather than replace them.
After vowing austerity during his campaign, he was now expected to ramp up spending, borrow abroad and dip into savings from export revenues gained by the key copper mining industry.
During his campaign, Pinera deflected accusations of potential conflicts of interest between his political ambitions and his corporate empire, promising to sell the bulk of his shares in airline LAN Chile before taking office.
He also successfully put a distance between himself and Pinochet’s dictatorship, which had enjoyed the backing of several right-wing parties now behind the billionaire.
Although Chile’s economy shrank 2% last year, its first contraction in a decade, it was forecast before the quake to grow between 4.5%-5.5% this year.
Pinera — who had pledged to boost annual growth to 6% as the Latin American model of economic success emerged from the financial crisis — was now under pressure to rebuild the nation.